1. Field of the Invention
The preferred embodiment relates to a universal serial bus (USB) storage device and, more particularly, to a USB storage device adapted to chip on board (COB) process.
2. Description of the Prior Art
Nowadays, USB is the most popular peripheral bus in computer industry and consumer electronic products. USB can be used to connect various peripheral devices, such as keyboard, mouse, flash driver, card reader, digital camera, personal digital assistant (PDA), smart phone, and so on. Due to plug and play capability and usage convenience, USB is available to most of applications in the market. So far there are lots of USB applications developed by peripheral and computer manufactures and there are also lots of drivers and programs developed correspondingly.
At present, a data transmission rate of USB 2.0 is 480 Mbps, and a data transmission rate of USB 3.0 is 5 Gbps, which is five times that of USB 2.0. Compared with USB 2.0, USB 3.0 may save much power. Furthermore, USB 3.0 is compatible with USB 2.0. Referring to FIGS. 1 and 2, FIG. 1 is a perspective view illustrating a conventional USB 3.0 plug 1, and FIG. 2 is a perspective view illustrating the USB 3.0 plug 1, which is shown in FIG. 1, equipped with a protecting casing 3. As shown in FIG. 1, the USB 3.0 plug 1 comprises four USB 2.0 flat pins 10 and five protruding pins 12. To prevent the protruding pins 12 from being damaged due to collision or other accidents, the conventional USB 3.0 plug 1 is always equipped with the protecting casing 3, as shown in FIG. 2. In general, the protecting casing 3 is made of metal, such as iron.
At present, most of portable electronic devices have a tendency to small size. The USB plug can be manufactured by chip on board process without the protecting casing 3, so as to achieve small size. However, if the aforesaid USB 3.0 plug 1 is manufactured by chip on board process, the five protruding pins 12 will be exposed out of the circuit board, such that the protruding pins 12 may be damaged due to collision or other accidents.